* {
    padding: 0;
    margin: 0;
}
html,
body {
    height: 100%;
    width: 100%;
}

.box {
    position: relative;
    margin: 0 auto;
    width: 300px;
    height: 300px;
}

.box > .smallBox,
.box > .bigBox {
    position: relative;
    width: 200px;
    height: 200px;
    border: 1px solid #000;
    min-width: 200px;
}
.box > .smallBox > .mask {
    position: absolute;
    left: 0;
    top: 0;
    width: 100px;
    height: 100px;
    background-color: rgba(0, 0, 0, 0.5);
}
.box > .smallBox > img {
    width: 100%;
}

.box > .bigBox {
    /* display: none; */
    position: absolute;
    top: 0;
    left: 200px;
    overflow: hidden;
}

.box > .bigBox > img {
    width: 200%;
}

.selectImg {
    display: flex;
    width: 200px;
    padding: 0;
    margin: 0;
}

.selectImg > li {
    list-style: none;
}

.selectImg > li > img {
    width: 50px;
    box-sizing: border-box;
    border: 1px solid transparent;
}

.selectImg > li > .active {
    border: 1px solid #000;
}
